1. Technical Field
The present invention relates to an image forming apparatus that is provided with a photoconductor, and an image forming method.
2. Related Art
In an imaging forming apparatus such as an electrophotographic copier and the like, for example, a toner image is obtained by charging a photoconductor drum, exposing selectively the photoconductor drum after the charging to form an electrostatic latent image and then developing the electrostatic latent image with toner charged to a predetermined polarity. Here, the photoconductor drum is provided with an electroconductive substrate made of, for example, a metal, and a photoconductor provided on a surface of the substrate. The photoconductor includes a monolayer photoconductor containing both a charge generation material and a charge transport material, and a multilayer photoconductor obtained by laminating a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material.
Typically, on a photoconductor, light-induced fatigue (light-induced fatigue refers to a state where a part of a photoconductor is exposed to light and the electric property thereof is temporarily changed compared with that of other parts) occurs after the photoconductor is exposed to light, and the exposure history remains in an image. In particular, when only a part of the photoconductor is exposed to light, there occurs a difference in image density between a portion exposed to light and a portion not exposed to light. Such a history is caused because an electric charge generated in the photoconductor by exposure to light is captured by a trap in the photoconductor.